Effect of environmental factors on rotifer population distribution in a two different ecosystems in northwest of Iran

Rotifers are microscopic aquatic animals of phylum Rotifera, which live in a diverse range of aquatic habitats. They are important in ecology of freshwater ecosystems by recycling nutrients and can alter trophic dynamic of planktonic communities. These features have also been used as indicators of the environmental conditions in aquatic habitats. Considering the important roles of this group of animals in the trophic chains of aquatic environments and the need to explore their biodiversity, this study was planned with the aim of analyzing patterns of rotifer community structure in Kani-Brazan and Bohlul-Kendi water bodies located in northwest Iran. Samples were collected seasonally between October 2007 and November 2008. Temperature, pH, DO, conductivity, salinity and rotifer abundance were measured. In total, 28 rotifer species were identified from the two studied sites. In each site, rotifer species diversity differed seasonally. Canonical correspondence analysis (CCA) was used to estimate the relationship between environmental variables and abundance of rotifer taxa. The clusters showed strong correlation with dissolved oxygen and electrical conductivity for shaping the rotifer assemblages in both Kani-Brazan and Bohlul-Kendi reservoirs.